The present invention relates to a method and a device for quickly freezing whole food such as edible meat, edible marine products and fabricated food.
The applicant of the present application acquired a patent right of Japanese Patent No. 2,011,591 (Japanese Patent Application Publication No. H7-28,710(1995) invented by the inventor of the present application. As mentioned in the specification of the patented invention, with a refrigerator equipped with a freezer compartment popular with a usual family, the interior of the freezer compartment is in general kept at a temperature within a range of approximately −20° C. to −23° C. for storing frozen edible meat or marine products. The freezing may occur in the condition that the products are in contact with gaseous matter in the freezer compartment.
However, freezing of a product of a certain size, for example, a thickness of the order of 20 mm may take approximately 4 to 5 hours in order to cool the product until its center portion is also cooled to the temperature in the freezer compartment so that the water content of the edible meat components is separated from the meat cells and is then frozen. When the meat is defrosted or unfrozen, the frozen water would flow out together with the blood of the meat as drips, thereby considerably destroying the flavor of the meat, causing a problem.
In order to solve this problem in the above patented invention, food in a hermetically sealed package is mechanically lowered into a nonfreezing liquid cooled at a temperature lower than −30° C. so as to be immersed therein, and the nonfreezing liquid is cooled from its four peripheries and, in addition, agitated to maintain its cold condition uniformly so that the food is cooled from its all the peripheries to its interior to a freezing temperature of −30° C. to −60° C. so as to be frozen for a short period of time of the order of a few tens minutes.
Namely, this patented invention solved the problem that how the cooling temperature is caused to pass quickly through the temperature zone (−1° C. to −5° C.), in which the maximum amount of frozen product may be produced, to lower the temperature of the food such as edible meat or the like from its outer peripheries while keeping the liquid surface contact of high-thermal conductivity.
On the other hand, a quick-freezing method whose temperature is as low as lower than −70° C. has been proposed. With such a proposal, however, only surfaces of food would be quickly frozen to form a poor thermal conductive zone and thereafter the interior of the food may expand by freezing to cause cracks, resulting in an unfavorable result.
Under these circumstances, however, the freezing method with liquid surface contact of the patented invention described above tends to make its device bulky so that its application may be limited to freezing of a great amount of food for business purposes, and suffers a disadvantage from the difficulty to use for general families or small businesses.